The use of conveyors provided with work holders for receiving and moving parts to a broaching machine and for holding the parts during the broaching operation as well as for other kinds of machining operations are known. Conveyors of this kind are generally loaded by a helper who stands at one end of the conveyor and as often as a work holder moves into position picks up the part to be operated upon and inserts it into the work holder. Such manual loading is extremely tedious and is an inefficient use of manpower. This invention relates to an automatic loader for eliminating manual disposition of the parts to be operated upon in the work holders. Further objects are to provide an apparatus for precision loading of the parts to be processed; to provide apparatus for loading while on the move and hence maximum capacity; to provide apparatus embodying release means for minimizing damage by reason of accidental lock-up between the parts and the travelling components of the loader; to provide apparatus which can be used not only to load but to unload the parts following processing; and to provide apparatus which can be quicly converted from automatic to manual use.